Device for storing temperature-controlled fluids

ABSTRACT

The invention relates to a device for storing temperature-controlled fluids, comprising at least one container ( 20 ), a Peltier element ( 30 ), the hot side ( 301 ) of which is in contact with at least one wall ( 201 ) of the container ( 209 ), at least one device ( 40 ) for delivering ambient air to the cold side ( 302 ) of the Peltier element ( 30 ), and at least one electrical energy source ( 50, 501, 502 ) for supplying the Peltier element ( 30 ) and the device ( 40 ) for delivering the ambient air. For low-loss storage of the fluid in the container ( 20 ), the device ( 40 ) for delivering ambient air can be operated according to the temperature of the ambient air and the heating capacity of the Peltier element ( 30 ) can be controlled according to the currently produced electrical energy of a photovoltaic solar generator ( 501 ) forming an electrical energy source. Preferably, times and/or durations of the heat energy emitted from the Peltier element ( 30 ) and/or from an accumulator ( 502 ) to the fluid can be controlled by a control appliance ( 6 ) on the basis of at least one requirements specification stored in the control appliance ( 60 ).

The invention relates to a device for low-loss storage oftemperature-controlled fluids, according to the preamble of claim 1.

A device for storing temperature-controlled fluids is known from GermanUtility Model DE 20 2009 015 549 U1. It is a device for heating waterwith the help of solar cells. The device comprises a photovoltaic solargenerator, to which a Peltier element connected to a fluid container,for example by means of a DC/DC converter, is connected.

The object of the invention is to provide a device for highly efficientgeneration and low-loss storage of temperature-controlled fluids, suchas water.

This object is achieved by a device having the features of claim 1.Advantageous embodiments of the invention are specified in the relateddependent claims.

With the present invention, highly efficient production and low-lossstorage of temperature-controlled fluids, such as water, is possible,depending on different requirement profiles. In particular, such phases,in which the photovoltaic solar generator generates no energy due tolack of sunlight, can be bridged by means of the device according to theinvention, without significant cooling of the fluid. The deviceaccording to the invention allows for extremely high efficiency, inwhich the electrical power used is converted by the additional use offree available heat into a multiple of heat. By means of the invention,a coefficient of performance (COP) of 2.2 on average can be achieved,whereas with cold fluid in the container and a low electric power, evenpeak COP values of 5 to 6 are achieved and this does not fall, evenunder the most unfavorable conditions, under 1.5. The invention thusenables a very efficient conversion of a supplied electric power into amultiple of heat energy of the fluid to be heated.

As an application of the invention, energy self-sufficient dwellingswithout connection to regulated supra-local power grids may serve as anexample.

The device for storing temperature-controlled fluids according to theinvention comprises at least one container and a Peltier element. Thehot side of the Peltier element is in contact with at least one wall ofthe container. In addition, at least one device is provided fordelivering warm ambient air and/or a heated fluid to the cold side ofthe Peltier element and at least one electrical energy source forsupplying the Peltier element and the device for delivering ambient airand/or a heated fluid. The fluid delivered for example by means of apump to the cold side of the Peltier element can come, for example, asrecovered heat from a waste heat exchanger, from a geothermal plant orfrom a solar thermal system, and thus, just as the ambient air, isdelivered with a much lower energy use than that amount of thermalenergy contained in the fluid.

The device for delivering ambient air and/or a heated fluid is operablefor low-loss storage of the fluid in the container as a function of thetemperature of the ambient air. This avoids the device for deliveringambient air to the cold side of the Peltier element being operated attimes when no energy can be generated in the photovoltaic solargenerator for applying to the Peltier element, for example at night. Ablowing onto the Peltier element with cold air is thus avoided, becausethat would lead in these phases, by an unavoidable heat conduction fromthe cold side to the warm side of the Peltier element, to an undesirablecooling of the fluid temperature in the container.

The heating power of the Peltier element is controlled as a function ofthe currently generated energy of the electrical energy sources, whichis designed in particular as a photovoltaic solar generator. Inaddition, the time and the duration of time and/or the heat energydelivered by the Peltier element to the fluid can also be controlled.This is done using at least one requirement profile, stored in a controlappliance, for providing the temperature-controlled fluid. As referencetimes, for example, sunrise and sunset can be used, but also personalhabits of the users of the device. For example, in a requirement profileit can be determined at what time of the day what amount of warm watershould be available in which temperature range. For example, everymorning at 7:00 am, 500 liters of warm water with a temperature of 40°C. should be available in the container.

In an advantageous development of the device according to the invention,a further energy source is formed by an accumulator. The accumulator ispreferably chargeable by means of the photovoltaic solar generator. Theaccumulator buffers and smooths the energy generated by the photovoltaicsolar generator and supplies the Peltier element regardless of thecurrently generated electrical power of the photovoltaic solar generatorwith the required electrical energy according to the respectiverequirement profile. With the help of the at least one requirementprofile, for example, a time grid for the connection and disconnectionof the accumulator for an actuation of the Peltier element can begenerated.

In an advantageous embodiment, a DC/DC converter is connected downstreamfrom the photovoltaic solar generator for adapting the voltage generatedby the solar generator to the useful voltage required by the Peltierelement or by the device for delivering ambient air. The photovoltaicsolar generator is thereby adaptable to the Peltier element by means ofthe DC/DC converter regulated either for a constant solar generatorvoltage or to maximum solar generator power.

An incoming heat loss of the fluid in the container is compensated bysupplying the Peltier element with a small amount of electrical energy.This is particularly necessary if the required warm air and/or sunlightis not possible—for example, during the night. By supplying the Peltierelement with a low electrical power of, for example, 1 W, the heatlosses of the fluid in the container, which otherwise occur due to heatconduction through the Peltier element, can be effectively andefficiently blocked off on the order of magnitude of approximately 5 to6 W.

In a particularly advantageous development of the device, the cold sideof the Peltier element is arranged in a vertically arranged channel forguiding the ambient air or forms part of a wall of this channel. Inaddition, a device for delivering ambient air is arranged in thechannel. This channel has at least one ascending and one descending partand a transition from ascending to descending part, which is closed atthe top.

At an inlet or outlet end, the channel particularly preferably has agrid and/or a plurality of pipes. By the air guide with a supply frombelow in the descending part and a downward discharge in the descendingpart, the heat loss in the device can be reduced. If the blower, whichis arranged in particular in the ascending part of the duct, standsstill, the cold side of the Peltier element is heated by its heatconduction to the temperature of the fluid in the tank. The air in thechannel heats up and remains due to the low density, which isresponsible for a buoyancy, in the channel, i.e. a standstill of the airresults. This thus transforms from a heat conductor into an insulator.As a result, heat losses can be prevented by convection. The grid and/orthe pipes are preferably formed from a poorly heat-conducting materialand prevent a turbulence of the air in the channel, in particular by anarrangement in an input region of the channel. As a result, heat lossescan be reduced by an external air movement.

According to a particularly advantageous development of the deviceand/or the channel, these have on at least one wall a heat-insulatinglayer of a plastic and/or of a natural material. As a result, theaforementioned possible heat loss can be additionally reduced. Theheat-insulating layer can be formed, for example, from polyurethanefoam, polystyrene plates or hemp plates.

In a further particularly advantageous embodiment of the entireapparatus for storing temperature-controlled fluids, the container canbe arranged in a spatially separate position relative to the at leastone electrical energy source. As a result, the device can also be usedin cramped or difficult conditions, for example, when the container mustbe placed at a different altitude than the solar generator. In contrastto a thermal solar generator, it is completely uncritical if thecontainer is higher than the photovoltaic solar generator, since onlyits electrical energy must be passed to the Peltier element and no hotwater must be pumped using additional electrical energy to thecontainer.

For a simple operation of the device, in a further development of theinvention, the at least one requirement profile can be entered byprogramming the control appliance by a user. Alternatively, the at leastone requirement profile can be established by measurements by means ofsensors which record the withdrawals of the fluid from the containeraccording to the time and the quantity. Advantageously, the controlappliance can be controlled and/or programmed via a remote control. Theremote control can be done via a mobile phone app.

Embodiments of the device according to the invention will be explainedin more detail with reference to the drawings. In the drawings:

FIG. 1 is a schematic overall view of the device for storage oftemperature-controlled fluids,

FIG. 2 is a schematic representation of the operation of the device in afirst exemplary embodiment,

FIG. 3 is a schematic representation of the operation of the device in asecond exemplary embodiment and

FIG. 4 is a schematic representation of the operation of the device in athird exemplary embodiment.

In a schematic representation of the device 10 in FIG. 1, a hot side 301of a Peltier element 30, due to its good thermal conductivity, abuts awall 201 of a container 20, which is filled with a heat-controlledfluid, such as water. A cold side 302 of the Peltier element 30,opposite of the hot side 301 thereof, abuts a heat sink 92.Alternatively to an abutment of the hot side 301 against the wall 201 ofthe container 20 or an abutment of the cold side 302 against a heat sink92, the hot side 301 and/or the cold side 302 may also be integrallyformed with the wall 201 and the heat sink 92.

The Peltier element 30 is connected to a photovoltaic solar generator501. The connection is made in this embodiment via a DC/DC converter 70.In an alternative embodiment, instead of the photovoltaic solargenerator 501, another electrical source 50 (not shown) may also beused.

The heat sink 92 resting against the cold side 302 of the Peltierelement 30 or integrally formed therewith is heated by the temperatureof the ambient air. In order to support this heating, a fan 807, whichmay be configured as a fan, is arranged on the cold side 302 of thePeltier element 30.

For heating the cold side 302 of the Peltier element 30, the supply of aheated fluid can additionally or alternatively be provided for thepurpose of delivering ambient air. This fluid delivered example by meansof a pump (not shown) to the cold side 302 of the Peltier element 30 cancome, for example, as recovered heat from a waste heat exchanger, from ageothermal plant or from a solar thermal system, and thus just as theambient air, be delivered with a significantly lower use of energy be tothe cold side 302 of the Peltier element 30, as this corresponds to theheat energy contained in the fluid additionally usable in the system.The efficiency of the entire system of container 20 and Peltier element30 is substantially improved by this additional use of free availableheat on the cold side 302 of the Peltier element 30.

In order to be able to remove as much electrical energy as possible fromthe photovoltaic solar generator 501, the DC/DC converter 70 isregulated via a control appliance 60. Thus, the photovoltaic solargenerator 501 can either be maintained at a constant solar generatorvoltage or at the point of maximum solar generator power (“MPPtracking”). The controller 60 is controlled by a remote control 62and/or is programmable.

In the event that the required warm air and/or sunlight is notavailable, which is usually the case, for example, at night, the fluidin the container 20 could be cooled by the thermal bridge formed by thePeltier element 30 and the heat sink 92. To prevent this, the Peltierelement 30 can be operated via an accumulator 502 even in these timeswith a low electrical power. With this small electrical power suppliedto the Peltier element 30 of, for example, 1 W, a much greater thermalpower loss, for example, 5 to 6 W is prevented.

In FIG. 2, a first exemplary embodiment of the device 10 is shown with adevice 40 having a heat sink 92 for delivering ambient air with achannel 80 having an ascending part 801 and a descending part 802. Thetwo parts 801 and 802 of the channel 80 are interconnected by atransition 803 which is closed at the top. In this case, the tubularhousing part of the descending part 802 has a smaller diameter than theascending part 801. In this first exemplary embodiment, the descendingportion 802 of the channel 80 is arranged laterally on the container 20.

The device 40 comprises a side wall 42 enclosing the device, a partitionwall 46 arranged between the ascending part 801 and the descending part802, and a cover 44 which delimits the transition 803 from the ascendingpart 801 to the descending part 802 upwards.

The container 20 is arranged in a region immediately following the sidewall 42. The Peltier element 30 is arranged in a partial area betweenthe side wall 42 and the container 20. In addition, a connecting line 22is formed near the side of the container 20 facing the device 40. Whenthe Peltier element 30 is heated by the warm fluid rising in it, theconnecting line 22 ensures circulation of the fluid in the container 20.

To reduce heat losses, the device 40 and the container 20 are providedwith a heat-insulating layer 806. This may consist of a plastic or ofnatural materials such as polyurethane foam, polystyrene plates or hempplates.

A nighttime cooling of the fluid in the container 20 can also beprevented or reduced by a reflector (not shown) being mounted around theheat sink 92 on the cold side 302 of the Peltier element 30, whichreflector reflects the heat radiation.

The heat loss can be additionally reduced by introducing an ambient airL40 into the ascending part 801 for air guidance and returning it as anair L through the descending part 802 again. In an outlet opening Aand/or in an inlet opening E of the channel 80, a grid 804 and/or pipes805 are provided. The grid 804 and/or the pipes 805 in the ascendingpart 801 of the channel 80 are adjoined by a fan 807 as part of thedevice 40 for delivering ambient air.

In this first embodiment, the device 40 for delivering ambient air andthe container 20 are formed from two separate and interconnectablecomponents. The connection is preferably by means of a non-positiveconnection such as screw or by means of a cohesive connection such aswelding or bonding.

In the second embodiment according to FIG. 3, the ascending part 801 ofthe channel 40 is arranged on the container 20. Grid 804 and/or pipes805 and the fan 807 are arranged analogously to FIG. 2. The same appliesto the side walls 42, the partition 46 and the cover 44. The ambient airL40 is introduced into the ascending part 801 through the inlet openingE, and leaves the outlet port A of the descending part 802 as air L.

The Peltier element 30 is arranged between the side wall 42 of thedevice 40 facing toward the container 20 and forming the cold side 302of the Peltier element 30 and a heat exchanger 94 arranged in thecontainer 20 forming the hot side 301 of the Peltier element 30. In theheat exchanger 94, the temperature-controlled fluid undergoes acirculating circulation process in which colder fluid F1 is sucked fromthe container 20 at the bottom thereof and heated fluid F2 is dischargedagain to the container 20 at the top thereof.

FIG. 4 shows a third exemplary embodiment of the device 10 in which thecontainer 20 is arranged above the device 40. The supply of the ambientair L40 is also realized via the inlet opening E of the ascending part801 of the channel 80, which is provided with a grid 804 and/or pipes805, which are formed as air channels, which is followed by a fan 807.The air L is passed through a heat sink 92, which is formed as aflow-through pipe and is preferably arranged at the partition 46perpendicular to the side walls 42. The Peltier element 30 is arrangedin the container 20 between the heat sink 92 forming the cold side 302in the device 40 and the heat exchanger 94 forming the hot side 301. Theheat sink 92 and/or the heat exchanger 94 may be formed according to anadvantageous embodiment of the invention as a so-called heat pipe (“heatpipe”).

The container 20 and the device 40 are formed in this exemplaryembodiment as a one-piece component, for example as a cast or producedby a coating method block.

In a further embodiment (not shown), a pipe, which has openings atdefined intervals, is arranged in the container 20 on the side facingthe hot side 301 of the Peltier element 30. Due to the difference indensity of the fluid in the container 20 due to the differenttemperatures in the container 20, a circulation of the fluid takesplace, which is based on the density difference of water with adifferent temperature. In addition, the heated water is then charged ina corresponding temperature zone of the container 20 (“layer charge”container 20).

The photovoltaic solar generator 501 charges the accumulator 502 shownin FIG. 1 with excess electrical energy which is temporarily notrequired for operating the Peltier element 30 and the blower 807 duringintense solar irradiation (operating mode: “Charging mode of theaccumulator 502”). The accumulator 502 then energizes the Peltierelement 30 in times when heat losses in the container 20 must beprevented (typically at night) or in which the photovoltaic solargenerator 501 alone cannot generate enough energy to produce therequired amount of heated fluid (e.g. at or before sunrise; operatingmode: “Heating by accumulator”).

By means of the invention, a COP (“coefficient of performance”) of onaverage 2.2 can be achieved, with cold fluid in the container 20 and alow electric power even a peak COP of 5 to 6 is achieved and this, evenunder the most unfavorable conditions, does not fall below 1.5. Theinvention thus enables a very efficient conversion of a suppliedelectric power into a multiple of heat energy of the fluid to be heated.

It is particularly advantageous if a clock in a microcontroller in thecontrol appliance 60 receives at least one reference point by measuringthe energy generated by the solar generator 501. This point of referencearises from the sunrise and the sunset, both of which result in asignificant change in the generated electrical energy at the solargenerator. In this case, the microcontroller can be additionallyconnected to a GPS receiver and a memory with a database on the localseasonal sunrises and sunsets. These reference points ensure thatdeviations of the clock, such as occur almost unavoidably over arelatively long period of time, can be corrected by the controlappliance 60. As a result, the user can always remove the desired amountof tempered fluid from the container 20 at the time he/she desires.

The accumulator 502 is also preferably used for a smoothing function byintercepting and storing peak powers of the solar generator 501, such asmay occur in cloud gaps, for example, so that the electrical energysupplied to the Peltier element 30 is always kept as evenly as possibleat a rather low level where the efficiency of the overall system ishighest.

The accumulator 502 is particularly preferably designed as a hybridstorage, with a lead-acid battery, which is preferably always charged asfully as possible and with a lithium-ion battery, which stores theremaining energy generated by the solar generator 501 and currently notrequired by the Peltier element 30. However, the accumulator 502 mayalso be formed only by a lithium-ion battery. Due to the advantageouscontrol by means of the control appliance 60, the Peltier element 30 isalways charged with the lowest possible power, which allows a high COPof 4 to 5, and the excess electrical energy stored in the accumulator502.

In order to make the system less sensitive to partial shading,additional bypass diodes are installed in the solar generator 501. Onebypass diode is preferably installed parallel to each twelve solar cellsor to an even smaller number of solar cells.

An added benefit of the invention is to utilize the heat sink created onthe cold side 302 of the Peltier element 30 to cool a room. The heat canbe removed from the room air by a suitable air flow or through asuitable fluid circuit.

It would also be possible to cool the solar cells of the solar generator501 itself and thereby enable a higher power production.

For reasons of efficiency, solar cells have so far rarely been used forhot water production. By the described device, the heat output comparedto pure electric solar cell power can be significantly increased. By thePeltier element 30 and the heat sink 92, heat is extracted from theenvironment, which is supplied to the container 20 together with theelectrical supply energy for the Peltier element 30. As a result, atotal amount of energy is supplied to the container 20, which issignificantly above the amount of energy that would be supplied only bythe electrical energy.

Compared to solar thermal water heaters, there is the advantage that theenergy which is conducted to the container 20 acting as a hot water tankis transported in easy-to-install cables in the form of electricalenergy and not by means of pipes in the form of warm water. By theenergy transport via electrical energy, the container 20 can also berelatively far away and placed independent of the altitude of the solargenerator 501. If the container 20 is arranged lower than the solargenerator 501, one does not need—as usual with solar thermal waterheaters—a pump for energy transport.

If the water outside the container 20 is additionally heated by a heatsource and supplied to the container 20 via pipes or hoses, this cyclecan be interrupted during the night by, for example, a device formed asa resistance valve device and heat losses in the container 20 canthereby be reduced.

Another advantage is that a photovoltaic water heater generates warmwater even at low ambient temperatures and low radiation power.

LIST OF REFERENCE SIGNS

-   10 device-   20 container-   201 wall-   202 connection line-   30 Peltier element-   301 hot side-   302 cold side-   40 device (for delivering ambient air)-   42 side wall (of 40)-   44 cover (of 40)-   46 partition (of 40)-   50 energy source-   501 solar generator-   502 accumulator-   60 control appliance-   62 remote control-   70 DC/DC converter-   80 channel (of 40)-   801 ascending part (of 80)-   802 descending part (of 80)-   803 transition (between 801 and 802)-   804 grid-   805 pipe-   806 layer (on 20 and 80)-   807 blower-   92 heat sink-   94 heat exchanger-   A outlet opening-   E inlet opening-   F1 fluid-   F2 fluid-   L air-   L40 ambient air

1. Device (10) for storing temperature-controlled fluids with at leastone container (20), having a Peltier element (30) whose hot side (301)is in contact with at least one wall (201) of the container (20), havingat least one device (40) for delivering ambient air (L40) to the coldside (302) of the Peltier element (30) and having at least one electricpower source (50) for supplying the Peltier element (30) and the device(40) with ambient air (L40), characterized in that for the low-lossstorage of the fluid in the container (20), the device (40) fordelivering ambient air (L40) is operable as a function of thetemperature of the ambient air (L40), and the heating power of thePeltier element (30) can be controlled as a function of the currentlygenerated electrical energy of a photovoltaic generator (501) formingthe electric energy source (50).
 2. Device (10) according to claim 1,characterized in that a further electrical energy source (50) is formedby an accumulator (502).
 3. Device (10) according to claim 2,characterized in that the accumulator (502) of the photovoltaic solargenerator (501) is chargeable.
 4. Device (10) according to one of thepreceding claims, characterized in that the photovoltaic solar generator(501) is connected to a DC/DC converter regulating the solar generatorvoltage (70).
 5. Device (10) according to claim 4, characterized in thatthe solar generator (501) with a DC/DC converter regulated to constantsolar generator voltage or maximum solar generator power (70) is adaptedto the Peltier element (30).
 6. Device (10) according to any one of thepreceding claims, characterized in that the heat loss of the fluid inthe container (20) can be compensated by supplying a small amount ofelectrical energy or by charging the Peltier element (30) with a lowelectric power.
 7. Device (10) according to any one of the precedingclaims, characterized in that the cold side (302) of the Peltier element(30) is arranged in a vertically disposed channel (80) for guiding theambient air (L40).
 8. Device (10) according to claim 7, characterized inthat the channel (80) comprises at least one ascending part (801) andone descending part (802) and a transition (803) from the ascending part(801) to the descending part (802), which is closed at the top. 9.Device (10) according to claim 7 or 8, characterized in that the channel(80) comprises, at least in sections, at least one grid (804) and/or aplurality of pipes (805).
 10. Device (10) according to at least one ofthe preceding claims, characterized in that at least one wall of thecontainer (20) and/or the channel (80) is provided with aheat-insulating layer (806).
 11. Device (10) according to at least oneof the preceding claims, characterized in that the container (20) can bearranged in a spatially separate position from at least one electricalenergy source (50; 501, 502).
 12. Device (10) according to one of thepreceding claims, characterized in that the cold side of the Peltierelement (30) can be heated alternatively or additionally to the ambientair (L40) by means of a further fluid.
 13. Device (10) according to oneof the preceding claims, characterized in that the time and/or the timeduration and/or the heat energy emitted to the fluid by the Peltierelement (30) is controlled by a control appliance (60) based on at leastone requirement profile for providing the temperature-controlled fluidstored in the control appliance (60), wherein the at least onerequirement profile can be entered in the control appliance (60) byprogramming by a user or can be calculated by means of an algorithmstored in the control appliance with values determined by sensors, whichmeasure the withdrawals from the container (20) by time and/or amountand/or measure temperature.
 14. Device (10) according to claim 13,characterized in that the control appliance (60) is controlled and/orprogrammable via a remote control (62).
 15. Device (10) according toclaim 14, characterized in that the remote control (62) can take placevia a mobile phone application.